| The booster pump cavitation may occur because of the drop in NPSHa of booster pump during the load rejection process of unit. It had become a serious threat to power plant safety operation. The maximum NPSHa decrease of booster pump (⊿NPSHamax) is determined by transient state characteristics of deaerator.Firstly, Basing on previous research achievements and experimental study on the600MW subcritical unit,the mathematical model is put forward to calculate the pressure, temperature of deaerator and booster pump entrance; the NPSHa of booster pump in the tripping process of sub-critical unit.Secondly, The⊿NPSHamax of ultra-super unit arises in RB process and could be measured to10meters, due to the design and operation control mode of ultra-super unit is different from sub-critical unit. The thermodynamic system state parameters have been measured in the RB process of a1000MW ultra-super unit. The parameters variation trend of deaerator and booster pump system has been carried out according to the research on measured data. Furthermore, on this basis the mathematical model to calculate the pressure, temperature of deaerator and booster pump entrance and the NPSHa of booster pump is presented in ultra-super unit RB process, by theoretical analysis on the RB transient process of deaerator. The accuracy of calculation model has been verified through the comparison between experiment data and computational results of the simulated test The calculation model could be popularly used in engineering practice.Lastly, the software to calculate the transient state characteristics of deaerator is developed on MFC platform. The application could compute the transient state characteristics of deaerator, the⊿NPSHamax of booster pump and estimate whether the booster pump cavitation occurred in the ultra-super unit RB transient and sub-critical unit tripping process. The software can import the unit data automatically by connecting with information design system of design institute through the excel. The workload to lay out the deaerator would be greatly reduced. |
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